JPS6067570A - Polyurethane insulated wire - Google Patents

Abstract

PURPOSE:To provide the titled insulated wire, having solderability and excellent crazing resistance, by coating a conductor with an insulation paint containing a crosslinking component containing a specific blocked isocyanate and a prepolymer having alcoholic OH group, at a specific ratio, and baking the paint. CONSTITUTION:(A) A crosslinking component comprising (a) a blocked isocyanate obtained by the reaction of (i) a diol having spiroacetal ring with (ii) a diisocyanate compound [e.g. the compound of formula (R1 is phenyl, methylphenyl, etc.; R2 is methylphenyl, diphenyl ether, etc.)] and (b) a blocked isocyanate having isocyanuric ring is mixed with (B) a prepolymer having alcoholic OH group at a ratio to give the reaction equivalent ratio of the NCO group of the component A to the OH group of the component B of 1 to 0.7-1.2, and the mixture is dissolved in an organic solvent. The obtained paint is applied to a conductor directly or via another insulation film, and backed to afford the objective insulated wire.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyurethane insulated wire that has brazing properties and excellent heat resistance and crazing resistance.

Polyurethane insulated wires have brazing properties that allow them to be soldered without peeling off the insulating film coated on the conductor, and are therefore widely used in coil windings for light electrical applications. With the recent miniaturization and weight reduction of equipment, the emergence of insulated wires that have higher heat resistance than the heat resistance of conventional polyurethane insulated wires, such as Class B or Class F, without compromising the soldering properties. is desired. Furthermore, polyurethane insulated wires have drawbacks such as crazing and generation of pinholes (underwater pinholes) when stretched to 3 inches, and preventing this has also been a technical issue.

The brazing properties and heat resistance properties of polyurethane insulated wires are in a trade-off relationship; improving one will impair the other. Conventionally, using a general polyisocyanate block as a crosslinking component has improved properties. Therefore, in the present invention, a new polyisocyanate block is synthesized, and an insulating paint made by dissolving this and an oligomer or prepolymer containing activated hydrogen in an organic solvent is coated and baked on a conductor to form a heat-resistant polyurethane. This is a successful insulated wire. On the other hand, various types of polyurethane insulated wires have been developed as an improvement over Crazing 2-9, but these generally have low thermal properties and, for example, can be activated as a polyol component blended into a polyincyanate block body, which is a crosslinking component. A general-purpose polyester prepoly with hydrogen and a hydroxyl equivalent of about 70 to 150 and a low molecular weight! - Instead of -, epoxy prepolymers with activated hydrogen, molecular weight of 40 o o, and hydroxyl group equivalent of about 300 are used. Crazing occurs when the voltage is applied and a pinhole test is performed.

In addition, methods of using bifunctional isocyanate blocks such as Schiff and pylmethane diisocyanate stabilized with xylenoleic acid as polyincyanate components have been taken, but this method does not completely prevent craze. It's impossible. The present invention has also succeeded in solving this problem of crazing resistance.

The new incyanate crosslinking agent developed by the present inventors is a diisocyanate (7' o-type) obtained by reacting a diol having a spiroacetal ring with a diisocyanate compound and blocking the remaining isocyanate groups with a phenolic compound. So, specifically, what type of diol has the structural formula % formula % spiroacetal ring? Since it has a pyroacetal ring as its backbone and alcoholic hydroxyl groups at both ends, it easily reacts with diincyanate compounds to form urethane bonds. This reaction was carried out with an excess amount of diincyanate, and the remaining isocyanate groups were blocked and stabilized with a phenolic compound. In comparison, the molecular chain is extremely long.

m Synthesis of spiroacetal-modified toluene diincyanate block (SPG-TDI-cresol crosslinking agent) Spiroacetal glycol 91 was placed in a four-piece parallel flask equipped with a temperature needle, a stirrer, a cooling tube, and a separating funnel.
．． 2F(0,5sol)9 as a reactive diluent
61.2F, triethylamine 0.8 as catalyst? Weigh and add toluene diisocyanate) and stir thoroughly to disperse it uniformly.
Add 0.4.4F (0.6 mol) and gradually drop the residue to react with the grain layer and acetal glycol. At this time, the temperature of the reaction system rises to about 70°C. Stir thoroughly during this time. When the temperature of the reaction system returns to room temperature, m-
64.89- of cresol is added and stirring is continued until it is confirmed that the infrared absorption band of incyanate reaches 22 aa. When the reaction was completed, m-cresol 348y- was added so that the solid fraction of the reaction system was 60-, thereby preparing a 5PG-TDI-cresol block solution.

Synthesis Example 2 Synthesis of spiroacetal-modified diphenylmethane diisocyanate block (SPG-MDI-cresol cross-linking agent) Spiroacetal glycol 91 was placed in a 4-tubular flask equipped with a thermometer, a stirrer, a cooling tube, and a separating funnel.
．． 27 (0.3 mol) 1 reaction diluent: Quizilol 3o6r, catalyst: triethylamine 0.8? Weigh and add and stir thoroughly to disperse evenly. Then, in a separatory funnel, add the weighed diphenylmethane diisocyanate)
150? (0.6 mol) was heated to 45° C. as a liquid and gradually added dropwise to react with spiroacetal glycol. At this time, the temperature of the reaction system is 50-60°
rises to C. During this time, stir thoroughly. When the temperature of the reaction system returns to room temperature, m-cresol 64.854 is further added to block the remaining isocyanate groups, and the infrared absorption band of isocyanate 6 is 2240. Continue stirring until it is confirmed that the When the reaction was completed, m-cresol 408 was added so that the solid part of the reaction system remained at 30 cm.
8PG-MDI-cresol block solution.

In addition to the bifunctional blocked inocyanate having a spiroacetal ring, a trifunctional blocked inocyanate having an isocyanate ring is used as a crosslinking component in the present invention. Isocyanur-modified triisocyanate block is CT-stable (Bayer, West Germany)
It is commercially available as a company product name).

The OH component for reacting with the difunctional and trifunctional blocked isocyanate crosslinking agent to form a urethane bond is a prepolymer having an al; S, 000 or more,
An epoxy prepolymer with a total weight of 300 equivalents of hydroxyl groups is used.

Examples Using the spiroacetal ring = 7- diisocyanate blocks and incyanur-modified triisocyanate blocks obtained in Intervention Examples 1 and 2 as crosslinking agents,
A prepolymer having an alcoholic hydroxyl group was blended with this in the composition shown in the table below, and the mixture was dissolved in a mixed solvent of cresol and kijirole to a resin concentration of 50% to prepare a polyurethane insulating paint.

This paint was applied to a copper wire having a conductor diameter of 0.35111 mm in a uniform thickness and baked to produce a polyurethane insulated wire according to the present invention.

Shown in the heat-resistant polyurethane insulation paint composition. As a comparative example, the characteristics of a conventionally known general-purpose polyurethane insulated wire that does not contain spiroacetal rings in the coating composition are shown.

8- As mentioned above, the blocked isocyanate crosslinking agent having a spiroacecool ring used in the present invention has an extremely long molecular chain compared to the conventional block diisocyanate, and the chain reacts with a prepolymer having an alcoholic hydroxyl group. In this case, the distance between crosslinks can be made longer, and the molecular structure of the insulating film becomes similar to a cylindrical molecule.

Therefore, in the polyurethane insulated wire according to the present invention, flexibility is imparted to the coating, and heat resistance is significantly improved due to the oxidation-resistant effect of the spiro ring having four oxygen atoms in the ring. That is, as is clear from the characteristic table, the residual ratio of the dielectric breakdown voltage value after heat deterioration, which indicates deterioration resistance, was as high as 59 to 68 T, and the heating loss curve of the insulating film showed a high T value.
The GI value also shows a high value of 142-152. At the same time, the problem of crazing, which had traditionally been a technical issue, was completely resolved. Furthermore, in the present invention, a difunctional block isocyanate having a spiroacetal ring and a pentafunctional block isocyanate having an incyanur ring are used together as the incyanate crosslinking component, so when only the bifunctional block isocyanate with a long molecular chain is used. This has the effect of preventing a decrease in the heat softening temperature p of the film, which occurs due to the low crosslinking density, without impairing the heat resistance.

The reason for limiting the reaction equivalent ratio of the NCO groups of the block isocyanate crosslinking agent to the OH groups of the prepolymer having alcoholic hydroxyl groups to a ratio of 1:0.7 to 1.2 is because if it deviates from this range, This is because if the crosslinking reaction is insufficient, the insulating film becomes thermally and mechanically brittle.

Claims (1)

[Claims] A block isocyanate obtained by the reaction of a diol having an acetal ring with a diisocyanate compound and a block isocyanate having a cyanuric ring are used as crosslinking components, and a prepolymer having an alcoholic hydroxyl group is added to both of the above blocks. The NCO groups of the isocyanate crosslinking agent and the OH groups of the prepolymer are added at a reaction ratio of 1:0.7 to 1.2, and the insulating paint dissolved in the organic lining agent is directly applied onto the conductor. Or a polyurethane insulated wire characterized by being coated and baked through another insulating film.